Polycarbonates are well known and have been widely employed for the production of thermoplastic molded articles.
Polycarbonate is a high-performance plastic with good impact strength. In addition to ductility (impact strength), general-purpose polycarbonate has high transparency, wide temperature limits (high impact resistance below -60.degree. C. and a UL thermal endurance rating of 115.degree. C. with impact), good dimensional stability high creep resistance and electrical properties which qualify it as sole support for current carrying parts (up to 125.degree. C. without loss of impact strength).
Polycarbonate has low water absorption, good stain resistance and a wide range of colorability. A weak area for polycarbonate is its relatively limited range of chemical resistance, which necessitates careful appraisal of applications involving contact with certain organic solvents, some detergents, strong alkali, certain fats, oils, and greases. Also, another weak area of polycarbonates is that they have high melt viscosities which makes them to some extent difficult to mold.
Attempts have been made to blend polycarbonates with various polymeric systems. Generally, the polycarbonate is not miscible with uniformity with the other polymer system. However, U.S. Pat. No. 3,218,372, for example, describes compositions of polyalkylene terephthalate and polycarbonate resins. These unreinforced compositions are described as having a reduced melt viscosity and as having a higher ductility than the polyalkylene terephthalate resins. Even in the occasional instances where the polycarbonate is miscible with the other polymer system, the properties which make polycarbonate a high performance plastic are generally reduced without additional advantages.